Mesenchymal Stem-Cell Transplantation for Hypoxic-Ischemic Brain Injury in Neonatal Rat Model

Abstract

Neonatal hypoxic-ischemic brain injury (HIE) remains a major cause of neurologic disabilities. However, many experimental therapies have shown limited successes. We assessed whether human mesenchymal stem cells (MSCs) could be transplanted in the HIE rat brain to improve neurologic disabilities. P7 SD rats were either subjected to left carotid artery ligation and hypoxic exposure [hypoxia-ischemia (HI)] or sham operation and normoxic exposure (sham). On P10, rat pubs received either PKH26-labeled MSCs or buffer via intracardial injection, resulting in four experimental groups: sham-buffer, sham-MSC, HI-buffer, and HI-MSC. Cylinder test and accelerating rotarod test were performed 14, 20, 30, and 40 d after injection. Six weeks after injection, cresyl violet and double immunofluorescence staining were performed. MSCs were transplanted to the whole brain mainly after HI. Glial fibrillary acidic protein and OX42 were more abundantly colocalized with MSC than neuronal specific nuclear protein or myelin basic protein. There were no significant differences in the total amounts and cell types between the lesioned and nonlesioned hemisphere. The lesioned hemispheric volume was decreased after HI (p ϭ 0.012) but not restored by MSC. Neurologic performance was significantly impaired only on the cylinder test after HI (p ϭ 0.034), and MSC transplants improved it (p ϭ 0.010). These suggest MSC can be a candidate for the treatment of neonatal HIE. (Pediatr Res 67: 42-46, 2010) H ypoxic-ischemic brain injury (HIE), a result of asphyxia at term, remains a major cause of neurologic disabilities. It occurs in ϳ20 of 1000 full-term infants. Between 20 and 50% of asphyxiated babies who exhibit HIE die during the newborn period. Of the survivors, up to 25% have permanent neuropsychological handicaps in the form of cerebral palsy, with or without associated mental retardation, learning disability, or epilepsy (1). However, except hypothermia, which has shown improvement only in mild to moderate HIE, many experimental therapies have met with limited success in the clinical environment (2).Neural stem cells have been proposed as a useful treatment modality for the diseases of the CNS including neonatal HIE in animal models. However, their lack of accessibility and the inhomogeneity in neuronal differentiation of various neurospheres limit their utility (3,4). Mesenchymal stem cells (MSCs), as cell-based therapy offer a potential source of therapies for various rodent models and clinical trials of human diseases such as Parkinson's disease, Huntington's disease, myocardiac infarction, and stroke (5-9). However, limited data are available in neonatal HIE models. Guan et al. (10) reported that more MSCs were transplanted to the neonatal rat brain when MSCs were intraperitoneally injected 2 h after hypoxia-ischemia (HI) than when they were injected in the sham group. Yasuhara et al. reported that when they injected MSCs into the hippocampus of neonatal HI rats, MSC survived 14 d after post-transplantation and helped behavioral...

Mesenchymal stem cells as a treatment for neonatal ischemic brain damage

“…Several experimental studies in neonatal models have shown that treatment with MSCs after ischemic brain injury has beneficial effects on functional outcome (26)(27)(28)(29). Lateralizing motor deficits are decreased by 40-70% after treatment with MSCs, although a decrease in lesion volume is not always reported (26)(27)(28)(29).…”

“…Intracranial injection of MSCs after neonatal ischemic brain injury in rodents improved functional recovery and reduced lesion size (27)(28)(29). Moreover, MSCs transplanted via the intravenous or intracardiac route also improved functional recovery (26,30). To circumvent the invasive procedure of local intracranial administration and the loss of cells after peripheral administration, we studied the possibility of using the intranasal administration route (31).…”

“…Although the detected number of intracranial transplanted cells is twofold higher after double MSC treatment, the majority of cells do not survive up to 3 d after transplantation (41). After intranasal or intracardiac administration of MSCs, it was possible to detect the cells in the brain over longer periods of time up to 6 wk after transplantation (26,32). It could be argued that migration of MSCs to the lesion site allows for a better adaptation of MSCs to the harsh ischemic environment, leading to better MSC survival than after intracranial transplantation early after transplantation.…”

“…It could be argued that migration of MSCs to the lesion site allows for a better adaptation of MSCs to the harsh ischemic environment, leading to better MSC survival than after intracranial transplantation early after transplantation. However, the number of MSCs surviving up to 4 wk after intracranial, intravenous, intracardiac, and intranasal transplantation is less than 1% (26,30,32,41), so the administration route has little to no influence on late graft survival. This number of surviving cells remains small in relation to the lesion volume and the number of MSCs that may integrate into the cerebral network is too little to cause the impressive effects just by mere differentiation of transplanted MSCs.…”

Rescuing the neonatal brain from hypoxic injury with autologous cord blood

“…However, differentiation has mainly been limited to GFAP þ astrocytes. [101][102][103] The inefficiency to undergo in vivo differentiation has also been observed following delivery of NSCs in the injured postnatal neocortex in animal models of HIE. Lee et al 104 reported that the majority of the donor cells remained undifferentiated or became astroglia, with only about 5% and 4% differentiation into neurons and oligodendrocytes, respectively.…”